What is the management approach for anemia?

Anemia Management Flowchart

Initial Classification and Workup

Begin by confirming anemia with hemoglobin <13 g/dL in men or <12 g/dL in women, then immediately classify by reticulocyte count and mean corpuscular volume (MCV) to guide your diagnostic and therapeutic pathway. 1

Step 1: Reticulocyte Count Assessment

• If reticulocytes >10×10⁹/L: This indicates regenerative anemia—proceed directly to hemolysis workup including peripheral smear, LDH, haptoglobin, and direct antiglobulin test 1
• If reticulocytes ≤10×10⁹/L: This indicates non-regenerative anemia—proceed to MCV classification 1

Step 2: MCV-Based Classification for Non-Regenerative Anemia

Microcytic Anemia (MCV <80 fL)

• Order iron profile immediately: ferritin, transferrin saturation (TSAT), reticulocyte hemoglobin equivalent (RetHe), and percentage of hypochromic red cells 1
• Iron deficiency confirmed if: ferritin <100 μg/L AND TSAT <20% (or <16% in inflammatory states), RetHe <29 pg, or hypochromic cells >10% 1, 2
• In men and postmenopausal women: Any confirmed iron deficiency mandates investigation for gastrointestinal blood loss—do NOT order fecal occult blood testing as it provides no diagnostic benefit 2
• Perform upper endoscopy with small bowel biopsy to screen for celiac disease 2
• Perform colonoscopy to evaluate colonic sources of blood loss 2
• In premenopausal women: Consider menstrual loss, menorrhagia, pregnancy, and breastfeeding as common causes, but women over age 45 require thorough GI investigation 2

Normocytic Anemia (MCV 80-100 fL)

• Check creatinine to assess for chronic kidney disease—monitor hemoglobin every 3 months if GFR <30 mL/min/1.73 m² 2
• Check CRP to identify inflammatory causes 1
• In inflammatory states: Ferritin interpretation changes—ferritin <100 μg/L with TSAT <16% suggests iron deficiency despite inflammation 2

Macrocytic Anemia (MCV >100 fL)

• Check TSH and free T4 to rule out hypothyroidism 1
• Check folate and vitamin B12 levels—nutritional deficiencies account for approximately one-third of anemia cases and should be checked at least annually 2
• Review medication history for drugs causing macrocytosis (methotrexate, anticonvulsants, alcohol) 2

Treatment Algorithms

Iron Deficiency Anemia Treatment

• Initiate oral iron supplementation as first-line therapy 3
• Expect hemoglobin to rise by 2 g/dL after 3-4 weeks of appropriate therapy 2
• Continue iron supplementation for 3 months after correction to replenish body stores 2
• Avoid parenteral iron in critical care patients except when used in conjunction with erythropoietin therapy 1

Vitamin B12 Deficiency Treatment

• Traditional intramuscular injections remain standard, though oral and intranasal preparations are available alternatives 3

Folate Deficiency Treatment

• Oral folic acid supplementation is straightforward and effective 3
• Recommend supplementation for all women of childbearing age to reduce neural tube defect risk 3

Critical Care-Specific Management

In critically ill patients, adopt a restrictive transfusion strategy with single-unit transfusion policy to minimize morbidity and mortality. 1

Prevention Strategies in Critical Care

• Implement phlebotomy reduction strategies to minimize iatrogenic blood loss 1
• Use red blood cells regardless of storage time when transfusion is indicated 1

Pharmacologic Treatment in Critical Care

• Administer erythropoietin to anemic critical care patients, especially after trauma, in the absence of contraindications 1
• Avoid routine iron therapy except when used in conjunction with erythropoietin 1

Common Pitfalls to Avoid

• Never rely on fecal occult blood testing for iron deficiency workup—it is insensitive and non-specific 2
• Do not interpret ferritin in isolation during inflammatory states—use TSAT <16% as the cutoff rather than <20% 2
• Do not undertreate older adults—failure to diagnose and manage anemia results in decreased quality of life, impaired cognition, impaired mobility, and increased mortality 4
• Do not stop iron supplementation when hemoglobin normalizes—continue for 3 months to replenish stores 2

Follow-Up Monitoring

• Repeat CBC in 4-6 weeks after initiating treatment to assess response 2
• In chronic kidney disease patients with GFR <30 mL/min/1.73 m²: Monitor hemoglobin every 3 months 2
• If anemia persists despite appropriate treatment: Refer to hematology for specialized evaluation 4